The present invention relates to lock spindle blind bolts and more particularly to a lock spindle blind bolt including a sleeve and a pin and having a lock collar inhibiting radial sleeve expansion by supporting the pin stop.
Blind bolts of the type of the present invention are designed for use in structural applications (in contrast to many blind rivets which are conventionally for non-structural uses). In addition, the blind bolt of the present invention is non-sleeve expanding or hole filling (which is also generally in contrast to conventional blind rivets). In aircraft applications, blind bolts are conventionally at or near maximum hardness in order to provide maximum strength. Hence the blind bolt of the present invention preferably is of the type shown and described in U.S. Pat. No. 3,253,495 issued to J. F. Orloff on May 31, 1966 and entitled "Hardened Blind Bolt With Annealed Shank Portion." Hence, the present blind bolt comprises a sleeve, a pin and a lock collar which function generally as shown and described in the subject Orloff patent. While the Orloff patent taught a unique construction for providing a gradient of hardness in the sleeve to enhance bulb formation, the present invention is directed to providing an improved pin stop and lock construction for locking the pin and sleeve together after the blind head has been formed. In this regard the lock is provided by a lock ring which is moved into a lock pocket defined by confronting cavities on the pin and the sleeve after a first mechanical stop between the pin and the sleeve is engaged. As the first mechanical stop is reached, the lock construction of the present invention becomes operative to supplement the stopping action to more positively assure that the travel of the pin is arrested.
As noted, blind bolts of the type of the present invention are non-sleeve expanding. In other words, such blind bolts do not perform a function of filling the mating holes in workpieces to be joined through sleeve expansion. In fact, the subject blind bolts are designed to be located in holes with a fit varying from a slight interference to a preselected clearance. With such blind bolts, the pin is stopped by engagement of stop shoulders on the pin and sleeve (shoulders 38 and 48 of Orloff, supra). As noted, the lock pocket is properly defined when the stop shoulders are engaged. In a clearance application, however, unless the lock is actuated to be set at the load when the pin and sleeve are appropriately aligned to properly define the lock cavity, the pin shoulder stop can radially expand the sleeve whereby it can override the sleeve shoulder stop. This could place the pin and sleeve lock cavities out of the desired alignment resulting in improper placement of the lock. Indeed, even if the lock is structurally satisfactory, the location of the pin a predetermined point beyond the sleeve could be aerodynamically unsatisfactory requiring either removal of the blind bolt or an auxiliary machining operation. These problems have been attended to with past constructions by carefully controlling tolerances of the lock and of the lock setting mechanism. In addition, while clearance applications are utilized, the amount of clearance is closely controlled such that the degree of radial expansion (until the hole inner walls are reached by sleeve expansion) is limited such that the stop shoulders can still adequately stop the pin. These problems have been greatly reduced with the present invention. In understanding the present invention, consideration of prior blind bolt lock constructions would be helpful.
Thus, prior blind bolt lock constructions have included the following:
1. Annular lock ring with double action tool; PA1 2. Shear flange with lock collar of corrugated construction, and PA1 3. Shear cap.
In the first construction (double action tool), the setting of the lock is dependent upon a shift mechanism of a tool. In the second construction, the ultimate shear load of the shear flange will determine the setting load of the lock collar portion; the shear cap operates in a similar manner. All of the above will be described in greater detail below. With the present construction, all of the loads are taken directly on the lock collar with resultant frictional loading against the pin; as will be seen, this mode of loading is controlled to provide an assist to the mechanical stop between the pin and sleeve whereby the likelihood of this stop being violated and the lock pocket being misaligned is minimized.
Therefore, it is an object of the present invention to provide a new blind bolt construction having a new and improved lock construction. It is a second object of the present invention to provide a new blind bolt construction.
It is advantageous to provide the blind bolt with a sleeve of substantially maximum hardness and/or strength. In this regard, the general sleeve construction in the Orloff patent, supra, could be advantageously used and, hence, the disclosure of that patent is incorporated by reference. Related subject matter regarding sleeve expanding and hence hold filling blind rivets can be found in U.S. Pat. No. 4,127,345 issued Nov. 28, 1978 to Angelosanto and Kendall (the present inventor), U.S. Pat. No. 4,230,017 issued Oct. 28, 1980 to Angelosanto, and U.S. Pat. application Ser. No. 175,723, filed Aug. 6, 1980 to Angelosanto and Kendall (the present inventor). All of the above can be considered as prior art relative to the subject invention.